七年之痒几何伤
[qī nián zhī yăng jĭ hé shāng]
'The geometrically-increased hurts seven-year-itch causes' refers to the troubles faced during relationships after they have lasted many years. Seven-year itch is believed to come from when the novelty has worn off and couples enter what might be more challenging times where challenges increase gradually (just like 'geometry growth'). Here geometry just emphasizes a fast-growing amount of pains.